Minocycline is a member of the broad spectrum tetracycline antibiotics, which has a broader spectrum than the other members of this group of compounds.
Minocycline is widely used in therapy, primarily to treat acne and rosacea at a once daily dose of 100 mg.
The preparation of minocycline is disclosed in U.S. Pat. No. 3,148,212; U.S. Pat. No. 3,226,436 and U.S. Pat. No. 4,849,136.
Minocycline may be used as base per se or as non-toxic acid addition salts of organic or inorganic acids, e.g. sulfonic, trichloroacetic or hydrochloric acid.
Minocycline base, previously known before this invention only in the amorphous form, is not as stable as the corresponding acid addition salts and hence, methods to provide a stable form of minocycline base which makes its use promising as an active ingredient have been examined.